Radio broadcast distributing system



June 5, 1928. 1,672,370

- E. E. CLEMENT RADIOBROADCAST DI STRIBUTING SYSTEM Filed July 5, 1924 3 Shets-Shet 1 l SERVlCi. SWITCH June 5, 1928.

Filed July 5, 1924 s, SHpeTs-Sheet 2 III M an \Gw E. lHt o m ww Fliiii fl em 3. m6 3... TNQTI June 5, 1928.

E. E. CLEMENT RADIOBROADCAST DISTRIBUTING SYSTEM Filed July 5, 19.24 s sheets-sheet 3 Patented June 5, 1928.

I entree STATE s PATENT QFFICE.

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Application filed; July 3,

My; invention relates tor systems of radio broadcast distribution and: has for its object the organization of a system-capable of giving service to subscribers in regional. groups, which may be related to each'other by a general organization corresponding to the long distance telephone organization, and is in the nature of an improvement or further development of the general type of system disclosed in my prior copending applications, Serial No. 699,023, filed; li hi-rch 13 1924, and Serial No. 701123 lil ed March 22, 1924, the latter patented January 6, 1925, as No. 1,522,362.

The object of the present invention is to provide a system of the above type which will afford the use of one ortwo audion tubes at the subscribei"s station,- for ex ample, a detector and amplifier tube and permit the use of the subscribers radio telephone re'eiving set simultaneously with the use of his main telephone set or an exten sion telephone set, while preventing substantially any reduction in the efficiency and strength of the radio set due to the extra draft of current from the line by the transmitter of the land telephone.

I attain the object of my invention by providing each subscriber with receiving radio telephone apparatus, and; providing at the central office radio receiving and retransmitting apparatus capable of receiving from long distances in any well known or other suit-able manner and relaying or transform-- ing the signals received into suitable form for efficient transmission thereof over the line circuits of the various subscribers. To enable the subscriber to operate his radio set for reception ofradio signals over either the wires or by pure radio during use of the telephone without detracting from the efficient operation of the radio telephone set due to the use of current by the telephone transmitter, I provide means for connecting the filament circuits of the one or two audion tubes at the subscribers station in series with the telephone transmitter which I find can be arranged to add suliicient re sistance to reduce the drop across the line at the subscribers station'without detracting from the quality of the telephone transmission, thus using the filaments to Serve the double function of energizing the tubes and addi g he n ce sary si to hold 1924.- Serial No. 729,193.

Fig. 3 is a diagram of a subscribers simplified circuit using one tube.

' Referring to thed-r'aw-ings in detail, and first to Figs. 1 and 2 the telephone circuits as shown in Fig. 1 are situated at the subscriber s substation and consistof the tip and sleeve or plus and minus line wires 1 and 2 leading into the subscribers station from the central ofiice. Connected to the linewires 1-2 is the usual subscribers telephone set T having the ringing condenser 3 and ringer 4 connected in series across the line through a radio choke coil 5, and a transmitter 6 arranged to be connected with the line in different circuit arrangements according to the use or nonuse ol the radio telephone as will be presently described. The subscribers telephone set also contains the usual induction coil 7 arranged to have its primary winding connccted in the circuitof the transmitter (:3 through the switch-hook contacts 8' and has its secondary winding connected in the receiver circuit The subscribers radio telephone receiving set comprises a detector tube D having its grid-filament or input circuitconnected to the moveable arms 13 l and 14 of the radio-service switch 15 which may take the form of any suit-able double throw or two way gangsw'itch having other blades or'moveable arms 16and 17 and an indicating arm 18 all on a common shaft 19. The lower stationary contacts 20'and 21 of this switch are connected across the terminals of the inductance 11 while the upper stationary contacts 22 and 22* also cooperating with the switch arms 13 and 14 are connected across the inductance 23 the upper terminal of which inductance is connected to the tuning condenser 23 to the plus line conductor 1. The switch arm 16 is connected through conductor 2 k to the minus line conductor 2 while its middle or oli contact 25 is connected through conductor 26 to the series return conductor 27 which leads to the plus line conductor 1 through the transmitter 6, switchhook contacts S, winding of induction coil 7, branch conductor 28 andv radio choke coil 5. The upper and lower contacts of the switch 16 are not wired. The central contact on which the switch arm 17 normally rests in the off position is not wired but the two '2;- treme or upper and lower contacts 29 and 30 are connected together through conductors 31 and 32 of the middle arm 33 of the telephone switch 34. The radio service switch 15 has thus three switching positions as indicated by the legends for the indicator arm 18, namely, Ofi, Local, and Long distance, for purposes which will later be described herein. The telephone switch 34L is also a three-positioned gang switch having an indicator arm 35 and two switching arms 33 36 movable in unison therewith. The switching arm 33 is-directly connected with the conductor 31 while the switching arm 36 is connected through conductor 37 and resistance 38 to the conductor31. The telephone switch has three positions as indicated by the legends associated with the indicating arm 35, namely, Radio, Radio with extension phone, and Radio with main phone. The switch arm 33 is arranged to connect the conductors 31-32 with the plus telephone line 1 through a suitable resistance such as the lamp 39 only in. the middle or radio position of the telephone switch 34;, while the switch arm 36 is arranged through its stationary contacts 4.1 and 42, to connect the wire 37 with the series return wire 27 or the transmitter circuit 43 of the extension telephone EX, which transmitter circuit is inductively coupled in the usual manner through the windings of the induction coil M to the telephone receivor 45. It will thus be seen that with the radio service switch in the position shown in the drawing, the off position, the radio telephone set will be disconnected and incapable of use because the input circuit of the detector tube D terminating in the switch arms 131tis open at'such switch anus, and the transmitter 6 of the subscribers land telephone set T is connected to the minus line wire 2 through the series return conductor 27, conductor 26, switch contact 25, switch arm 16, and a conductor 24. Under this condition the subscribers land telephone T is connected to the line in the usual manner exceptior the insertion of the radio choke coil 5. The subscribers set is also provided with an amplifier tube A coupled in the usual manner through a radio transformer 46, a detector jack. 47 to the plate circuit conductor 4-8 which leads through a feed back coil 49 to the plate of ductors 27 the detector tube D. The output or plate circuit of the amplifier A is connected across the line wires 1-2 with a single stage amplifier jack 50 in series for the insertion in said output circuit of a suitable receivstation is provided a pluralityof the opera-- tors interconnecting cord circuits one of which is here shown and consists of. the usual answering and calling plugs and 56 respectively, with the usual listening key 58, ringing key 57, common battery supply 59, repeating coil 66 and talking condensers-z 61 and 62, connecting and operating in the usual manner as well understood in the art and which will be more clearly brought out in the description of operation to follow. In addition to the usual common battery 59, the operators cord circuit is provided with a booster battery 63 arranged to be thrown in series with the battery 59 by means of the double polo double throw switch arms 64 and 65 cooperating with the contacts 66-67 and 6869, respectively.

The central office is also provided with a suitable radio relaying or transmitting apparatus 70 having its output conductors 7j1.-7 2 arranged to be connected through switch 73, to conductors 74l75 constituting a radio bus to which a subscribcrs line may be connected through a radio aclc'? 6.

In the operation of the system shown in Figs. 1 and 2, using the 2-t-ube subscribers radio receiving set, and with the various switches at the subscribers station in the position shown in Fig. 1, the subscriber may close his telephone line 1-2 through his transmitter 6 for signalling the central office by raising his receiver 108 in the usual manner. The circuit of the transmitter 6 across the telephone line may be traced from line wire 1, through radio choke coil 5, con ductor 28, winding of induction coil '1, switchhook contacts 8, t-lFtDSD'llttGl 6, con- 26, 25, 16, 24-, to line wire 2. This closure of the subscribers line circuit signals the central oflioe operator through the usual central oflice line signal not here shown as they form no essential part of the present invention and may be of any known or other suitable form. Vith the subscribers circuits and apparatus in the condition shown in Fig. 1 he may also be signalled from the central office inthe' usual lfiil manner by the application. of a ringing current to his line Wires 1Y-2\ the circuit for which may be traced from line 1', through elements 5, 28, ringer a, condenser 3, to line wire 2..

When the subscriber desires radio service, he signals the central oliice operator in the usual manner, and the operator inserts her answering plug. in the [subscribers jack 52 and. actuating her listening key 58 establishes communication with the calling subscriber through her cord circuit over the line in: the usual manner and ascertaining the. subscribers wish for radio service inserts the plug 56 of the same cord circuit in the radio jack 76, and throws the switch arms 64-6'5 into engagement with the contacts 66-68. The subscribers line is now supplied with battery current from the main battery 59 and. booster battery 63 in series, the. circuit of which battery supply may be traced from battery 59, through battery 63, repeating coil winding 80, cord conductor 81, cord. conductor 82, tip contact. of plug 56, tip contact of jack 52, subscribers line conductor 88, line wit-e1, to subscribers station of Fig, 1', and back from subscriber-7s station by way of line. conductor 2,. conductor .84, sleeve of jack 52, sleeve of plug 55 cordcond-uctor 85, cord conductor 86, Winding 87 of repeat coilYGO, conductor 88, 111Gb conductor: 89. back to battery 59. Thus both batteries 59 and are connected in series across the subscribers line wires 12 for current supply tothe. subscribers station the wire 1 being plus and the ,wire 2 being minus. As the batteries are each approximately of 25volts the potential thus put upon the subscribers line with the line circuit open is approximately 50 volts, The subscriber is now able to receive either local broadcast over his antenna 9 or long distance broadcast relay from the central ofiiceover his line wire by moving, the switch indicatorarm 18 into either the local or long distance position, respectively. If he 'desireslocal broadcast and moves the arm 18 down into the position indicated as local, the switch arms 1314 will engage the contacts 20 and 21 or connect the input circuit of his detector tube D with the antenna ground connection 9l2.. This connection may be traced from antenna 9 through the wave length tuning condenser 10 and in parallel through the inductance 11 to the ground 12 and from the upper terminal of the inductance 11 through contacts 2013 to the grid of the detector tube D and from. the filament thi-ough contacts 1 l-2 1 to the lower terminal inductance 11. The filaments the subscribers detector tube B and amplifier tube A are energized in series ,by current from line wire 1 through resistance lamp 39, switch contact 40, switch arm 33,. conductors 32 and 31,. contacts30 and 17,

D,, resistance element 90, filament of; tube A to'line wire. 2. The resistance of the lamp filaments and the elements 39 and 90 is such as to permit the lamp filaments to be supplied withthe proper amount of current, which resistance is also sullicient to hold the line voltage at su'l'hcient amount to supply tliienecessary working potential to the plate circuits of the; tubes allowing for the drop in voltage due to the flow of current through the line resistance.v The plate circuit for the detector tube D may be traced from linewire 1 through contacts of jack 4?, condu-ctor 4E8, tickler coil 49, to the plate electrode of tube 'D and from thence by way of the filament through resistance element 90 and'filament of tube A to the line wire 2. The plate circuit of the amplifier tube A may be traced from line wire 1 through jack 50 and loud speaker 51 to the, plate element of the tube A and from thence by way of the filament oftube A directly to the line wire 2. Thus the full potential oi the line, allowing for the drop due to the flow of current through the filaments, is applied to the amplifier plate while the potential on the plate of the detector D is somewhat less than theline' potential due to the How oii current through the resistance 9. This gives the tubes proper different plate voltages for efiicient operation as detector and amplifier respectively. It desirable the subscriber may listen in on. the output circuit of the detector tubeonl y, by way ofthe first stage jack 4?, by the use of the loud speaker 51 or the usual head set not shown.

When the subscriber desires to receive long distance matter relayed from the central ofiice he moves the indicator arm 18 of the radio service switch up into the long distance position which preserves the ch cult of the tube filaments by moving the contact 17 into engagement with the contact 29, but

disengages the switch arms 13 14, whichform the terminals of the input circuitof the detector, from the contacts 202 1. and moves them into engagement with contacts 22 -22 which places the input circuit across the terminals of the long wave inductance 23. This position of the radio service switch also connects the inductance 23 in series with the tuning condenser2if across the line wires in a circuit which may be traced from line wire 1, through condenser 28,- inductance 23, contacts 2214, filament of tube D, rmsistance element 90, filament of tube A, to the line wire 2. The subscribers radio receiving circuit is now in condition to receive the long wire-guided waves supplied over his line circuit 12 from the central ofiice relay trans mitter 70. This relay transmitter may be of any known or other suitable form operable .to receive signals from long distance and relay the same as modulations on a long carrier filament of tube Wave. distributed over the subscribers line,

or it may take the form of any suitable source of long wave transmitter and modulator capable of distributing modulated long waves over the subscribers lines. The path of the long waves from the source 70 at the central oifice Fig. 2 to the subscribers station Fig. 1 may be traced from the source 70, through elements 71, 73, 74, tip of radio jack 76, tip of calling plug 56, S2, 81, audio or telephone condenser 62, tip of answering plug 55, tip of jack 52, 83, line wire 1, to Fig, 1, long wave tuning condenser 23, 22, 23, 22, 1-1, filament of tube D, 90, filament of tube A, back over line wire 2 to Fig. 2, 84C, sleeve of line jack 52, sleeve of answering plug 55, audio or telephone condenser 61, 86, 85', sleeve of calling plug 56, sleeve of radio ack 7 6, 75, 72, back to the source 70.

When the subscriber desires to use either his extension telephone EX or the main telephone T, for the purpose of making a call or communicating with the central oftice or broadcast station without interrupting his radio service, he may do so by moving the indicator arm of his telephone service switch 34 to the position marked Radio with ext. phone or the position marked Radio with main. phone as the case may be. With the indicator arm in the left hand position, the switch arm 33 is moved out of engagement with the contact and the switch arm 36 is moved into engagement with the contact 42 thus opening the direct communication of the filament circuit with line wire 1 through contact 40 and closing the filament circuit to line wire 1 through contacts 36-4-2 and the transmitter circuit 43 of the extension telephone which connection may be traced from line wire 1, through elements 43, 42, 36, 37, 38, 31, contact 29 or 30 according to the position of the radio service switch 70, thence through the lamp filaments to line wire 2. As the transmitter circuit 4L3 of the subscribers extension telephone EX is now bridged across the line he may communicate with the central or broadcast station in the usual manner. When the indicator arm 35 of the telephone service switch is moved to the right hand position, the switch arm 33 is moved to the right out of engagement with the contact 40 which opens the direct communication of the filament circuit to line as before, while the switch arm 36 is moved into engagement with the contact 41 which connects the filament circuit across the line in series with the transmitter circuit of the main telephone T which circuit connection may be traced from line wire 1, through elements 5, 28, 7, 8, 6, 27, 41, 36, 37, 38, 31, contacts 29 or 31 according to the position of the radio service switch 17, filaments of tubes D and A, to line wire 2. a

The subscriber is thus able to make use of his telephone line for telephone purposes without interfering with the use of his radio telephone receiving set and by the PIOVlsion of the extension phone in proximity to his radio telephone receiving set is enabled to establish immediate communication'with the broadcasting station for the purpose of applause or the like without having to interrupt his radio reception.

The subscribers simplified radio receiving set of Fig. 3 'is identically the same as that of Fig. 1 except that before one tube, the detector tube D is used, a telephone headset 151 is used instead of a loud speaker.

Having thus described my invention, what is claimed and desired to be secured by Letters Patent is:

1. A radio telephone distributing system, comprising in combination with a common battery telephone exchange system, telephone apparatus at the subscribers stations operable on the normal telephone line voltage, radio receivers at the subscribers stations having current consuming devicesarranged to take current fromthe subscribers lines and requiring a voltage higher than the normal telephone line voltage, a booster current source at the telephone central office and means to connect the same for increasing the potential on a given line when its radio receiver is in service sufliciently to operate the said'high voltage current consuming device associated with that line, and means for connecting a portion of the radio receiver in series with the said normal voltage telephone apparatus to'protect the latter against the increased potential.

2. The combination with a common battery telephone exchange system, having a normal or a low voltage transmitter at the subscribers stations of a radio receiver at a subscribers station having a thermionic tube connected to the subscribers telephone line for energization therefrom of its filament and plate circuits, said plate requiring a higher voltage than the normal voltage of the line, means at the central office for boosting the line voltage on a given line when its radio receiver is in service to the voltage required to operate the said plate circuit, and resistance means arranged to be connected in series with the filament of the thermionic tube and the normal voltage telephone transmitter of sufiicient resistance to maintain the required current flow throu h the filament and protect the said normal vo tage transmitter against the higher voltage;

3. The combination with a common battery telephone exchange system having main telephone sets at the subscribers stations in which the transmitter circuit is connected in series with the subscribers teletube, an-extension telephone set associated' with the subscribers radio receiver and switching means for connecting the filament of the triode tube in series with either the transmitter of the main telephone set or the transmitter of the extension telephone set.

4:. The combination with a common battery telephone exchange system having main telephone sets at the subscribers stations energized over the line, of a radio receiver and an extension telephone associated therewith at the subscribers station and switching means for connecting the subscribers radio receiver for energization in series with either said main telephone or said extension telephone.

5. The combination with a common battery telephone exchange system having main telephone sets at the subscribers stations energized over the subscribers line, of a radio receiver and an extension telephone set associated therewith at the subscribers station, resistance means at the subscribers station, said resistance means and each of said main telephone and extension telephone having substantially the same resistance, and switching means for connecting the energizing circuit of said radio receiver in series with either one of said resistance means, main telephone, or extension telephone, alone.

6. In a common battery telephone exchange system having telephone exchange system apparatus at the subscribers statlon operable on the normal telephone line voltage, the combination of a triode audion tube situated at the subscribers station and requiring for its plate circuit a voltage higher than the said normal voltage, means for increasing the voltage on a given line to that required by the plate circuit of the triode tube, said triode tube having its filament circuit arranged to be connected in series with said normal voltage telephone apparatus when the line voltage is increased to protect the telephone apparatus against increased voltage. v

In testimony whereof I hereunto afiix my signature.

EDWARD E. CLEMENT. 

